/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 *
 */
package org.hibernate.event.def;

import org.hibernate.LockMode;
import org.hibernate.ObjectDeletedException;
import org.hibernate.cache.CacheKey;
import org.hibernate.cache.access.SoftLock;
import org.hibernate.engine.EntityEntry;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.engine.Status;
import org.hibernate.persister.entity.EntityPersister;
import org.hibernate.pretty.MessageHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A convenience base class for listeners that respond to requests to perform a
 * pessimistic lock upgrade on an entity.
 *
 * @author Gavin King
 */
public class AbstractLockUpgradeEventListener extends AbstractReassociateEventListener {

	private static final Logger log = LoggerFactory.getLogger(AbstractLockUpgradeEventListener.class);

	/**
	 * Performs a pessimistic lock upgrade on a given entity, if needed.
	 *
	 * @param object The entity for which to upgrade the lock.
	 * @param entry The entity's EntityEntry instance.
	 * @param requestedLockMode The lock mode being requested for locking.
	 * @param source The session which is the source of the event being processed.
	 */
	protected void upgradeLock(Object object, EntityEntry entry, LockMode requestedLockMode, SessionImplementor source) {

		if ( requestedLockMode.greaterThan( entry.getLockMode() ) ) {
			// The user requested a "greater" (i.e. more restrictive) form of
			// pessimistic lock

			if ( entry.getStatus() != Status.MANAGED ) {
				throw new ObjectDeletedException(
						"attempted to lock a deleted instance",
						entry.getId(),
						entry.getPersister().getEntityName()
				);
			}

			final EntityPersister persister = entry.getPersister();

			if ( log.isTraceEnabled() )
				log.trace(
						"locking " +
						MessageHelper.infoString( persister, entry.getId(), source.getFactory() ) +
						" in mode: " +
						requestedLockMode
				);

			final SoftLock lock;
			final CacheKey ck;
			if ( persister.hasCache() ) {
				ck = new CacheKey( 
						entry.getId(), 
						persister.getIdentifierType(), 
						persister.getRootEntityName(), 
						source.getEntityMode(), 
						source.getFactory() 
				);
				lock = persister.getCacheAccessStrategy().lockItem( ck, entry.getVersion() );
			}
			else {
				ck = null;
				lock = null;
			}
			
			try {
				if ( persister.isVersioned() && requestedLockMode == LockMode.FORCE ) {
					// todo : should we check the current isolation mode explicitly?
					Object nextVersion = persister.forceVersionIncrement(
							entry.getId(), entry.getVersion(), source
					);
					entry.forceLocked( object, nextVersion );
				}
				else {
					persister.lock( entry.getId(), entry.getVersion(), object, requestedLockMode, source );
				}
				entry.setLockMode(requestedLockMode);
			}
			finally {
				// the database now holds a lock + the object is flushed from the cache,
				// so release the soft lock
				if ( persister.hasCache() ) {
					persister.getCacheAccessStrategy().unlockItem( ck, lock );
				}
			}

		}
	}

}
